Network slice reselection

ABSTRACT

A WTRU ( 102 ) may receive updated assistance information for network slice selection and/or reselection ( 410 ). The WTRU may apply local policies to determine when to use the updated assistance information to access a network slice ( 440 ). The WTRU may determine whether to contact an existing network slice function ( 470 ) or a new network slice function ( 460 ) to establish a connection to a network slice. Based on the determination, the WTRU may transmit different information to the network. The network slice selection and/or reselection may be initiated by a WTRU or by a network.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 U.S.C. § 371of International Application No. PCT/US2017/046218, filed Aug. 10, 2017,which claims the benefit of Provisional U.S. Patent Application No.62/375,843, filed Aug. 16, 2016, and Provisional U.S. Patent ApplicationNo. 62/454,450, filed Feb. 3, 2017, the contents of all of which areincorporated herein by reference in their entireties, for all purposes.

BACKGROUND

Mobile communications continue to evolve. A fifth generation may bereferred to as 5G. A 5G network may be configured to providedifferentiated services through network slices. For example, the networkmay provide personal phone services in a first network slice, criticalservices (e.g., public safety) in a second network slice, and Internetof Things (IoT) services (e.g., sensors, machines, etc.) in a thirdnetwork slice. A wireless transmit/receive unit (WTRU) may register witha network to access one or more of network slices.

SUMMARY

Systems, methods, and instrumentalities are disclosed for network sliceselection and/or reselection. A WTRU may receive a message from anetwork. The message may include updated network slice information. Theupdated network slice information may be transmitted by the network inresponse to a subscription change or a mobility change associated withthe WTRU, for example. The WTRU may determine that at least a firstnetwork slice being utilized by the WTRU can no longer be used by theWTRU based on the updated slice information. The WTRU may be served by afirst access and mobility management function (AMF) of the network forat least the first network slice. The WTRU may have a temporaryidentifier that is associated with the first AMF.

The WTRU may possess network slice selection assistance information(NSSAI). The WTRU may update the NSSAI based on the updated networkslice information. The WTRU may have one or more configured policies.The WTRU may determine, based on the updated network slice informationand the one or more configured policies, that the first network sliceshould be replaced with a second network slice.

Further, the WTRU may contact a first AMF or a second AMF to establish aconnection to the second network slice. The WTRU may determine whetherthe first AMF should serve the WTRU for the second network slice. If theWTRU determines that the first AMF should serve the WTRU for the secondnetwork slice, the WTRU may transmit a connection or registrationmessage comprising the updated NSSAI to the first AMF. If the WTRUdetermines that the first AMF should not serve the WTRU for the secondnetwork slice, the WTRU may delete the temporary identifier associatedwith the first AMF and transmit a connection or registration messagecomprising the updated NSSAI to the second AMF.

The updated NSSAI may identify a type of service provided by the secondnetwork slice. The type of service may include at least one of anenhanced Mobile Broadband (eMBB) service, an ultra-reliable low latencycommunications (UR-LLC) service, or a massive Internet of Things (mIoT)service. The policies configured for the WTRU may include informationregarding a list of network slices that the WTRU is permitted to access.The WTRU may determine to replace the first network slice with thesecond network slice upon selecting the second network slice from thelist of network slices that the WTRU is permitted to access.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a system diagram illustrating an example communicationssystem in which one or more disclosed embodiments may be implemented.

FIG. 1B is a system diagram illustrating an example wirelesstransmit/receive unit (WTRU) that may be used within the communicationssystem illustrated in FIG. 1A according to an embodiment.

FIG. 1C is a system diagram illustrating an example radio access network(RAN) and an example core network (CN) that may be used within thecommunications system illustrated in FIG. 1A according to an embodiment.

FIG. 1D is a system diagram illustrating a further example RAN and afurther example CN that may be used within the communications systemillustrated in FIG. 1A according to an embodiment.

FIG. 2 shows an example of a network slicing architecture.

FIG. 3 shows another example of a network slice architecture with anindependent network slice selection function (NSSF).

FIG. 4 shows an example of WTRU-initiated network slice reselection.

FIG. 5 shows example call flows for network slice reselection.

FIG. 6 shows example message flows in an example back-off mechanismrelated to network slice selection.

DETAILED DESCRIPTION

A detailed description of illustrative embodiments will now be describedwith reference to the various Figures. Although this descriptionprovides a detailed example of possible implementations, it should benoted that the details are intended to be exemplary and in no way limitthe scope of the application.

FIG. 1A is a diagram illustrating an example communications system 100in which one or more disclosed embodiments may be implemented. Thecommunications system 100 may be a multiple access system that providescontent, such as voice, data, video, messaging, broadcast, etc., tomultiple wireless users. The communications system 100 may enablemultiple wireless users to access such content through the sharing ofsystem resources, including wireless bandwidth. For example, thecommunications systems 100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailunique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM(UW-OFDM), resource block-filtered OFDM, filter bank multicarrier(FBMC), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a RAN104/113, a CN 106/115, a public switched telephone network (PSTN) 108,the Internet 110, and other networks 112, though it will be appreciatedthat the disclosed embodiments contemplate any number of WTRUs, basestations, networks, and/or network elements. Each of the WTRUs 102 a,102 b, 102 c, 102 d may be any type of device configured to operateand/or communicate in a wireless environment. By way of example, theWTRUs 102 a, 102 b, 102 c, 102 d, any of which may be referred to as a“station” and/or a “STA”, may be configured to transmit and/or receivewireless signals and may include a user equipment (UE), a mobilestation, a fixed or mobile subscriber unit, a subscription-based unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watchor other wearable, a head-mounted display (HMD), a vehicle, a drone, amedical device and applications (e.g., remote surgery), an industrialdevice and applications (e.g., a robot and/or other wireless devicesoperating in an industrial and/or an automated processing chaincontexts), a consumer electronics device, a device operating oncommercial and/or industrial wireless networks, and the like. Any of theWTRUs 102 a, 102 b, 102 c and 102 d may be interchangeably referred toas a UE.

The communications systems 100 may also include a base station 114 aand/or a base station 114 b. Each of the base stations 114 a, 114 b maybe any type of device configured to wirelessly interface with at leastone of the WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to oneor more communication networks, such as the CN 106/115, the Internet110, and/or the other networks 112. By way of example, the base stations114 a, 114 b may be a base transceiver station (BTS), a Node-B, an eNodeB, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller,an access point (AP), a wireless router, and the like. While the basestations 114 a, 114 b are each depicted as a single element, it will beappreciated that the base stations 114 a, 114 b may include any numberof interconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104/113, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals on one or morecarrier frequencies, which may be referred to as a cell (not shown).These frequencies may be in licensed spectrum, unlicensed spectrum, or acombination of licensed and unlicensed spectrum. A cell may providecoverage for a wireless service to a specific geographical area that maybe relatively fixed or that may change over time. The cell may furtherbe divided into cell sectors. For example, the cell associated with thebase station 114 a may be divided into three sectors. Thus, in oneembodiment, the base station 114 a may include three transceivers, i.e.,one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and mayutilize multiple transceivers for each sector of the cell. For example,beamforming may be used to transmit and/or receive signals in desiredspatial directions.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet(UV), visible light, etc.). The air interface 116 may be establishedusing any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104/113 and the WTRUs 102 a,102 b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 115/116/117 using wideband CDMA (WCDMA).WCDMA may include communication protocols such as High-Speed PacketAccess (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-SpeedDownlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access(HSUPA).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as Evolved UMTS TerrestrialRadio Access (E-UTRA), which may establish the air interface 116 usingLong Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/orLTE-Advanced Pro (LTE-A Pro).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as NR Radio Access, which mayestablish the air interface 116 using New Radio (NR).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement multiple radio access technologies. For example, thebase station 114 a and the WTRUs 102 a, 102 b, 102 c may implement LTEradio access and NR radio access together, for instance using dualconnectivity (DC) principles. Thus, the air interface utilized by WTRUs102 a, 102 b, 102 c may be characterized by multiple types of radioaccess technologies and/or transmissions sent to/from multiple types ofbase stations (e.g., a eNB and a gNB).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.11 (i.e.,Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperabilityfor Microwave Access (WiMAX)), CDMA2000, CDMA2000 1×, CDMA2000 EV-DO,Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), InterimStandard 856 (IS-856), Global System for Mobile communications (GSM),Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and thelike.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, an industrialfacility, an air corridor (e.g., for use by drones), a roadway, and thelike. In one embodiment, the base station 114 b and the WTRUs 102 c, 102d may implement a radio technology such as IEEE 802.11 to establish awireless local area network (WLAN). In an embodiment, the base station114 b and the WTRUs 102 c, 102 d may implement a radio technology suchas IEEE 802.15 to establish a wireless personal area network (WPAN). Inyet another embodiment, the base station 114 b and the WTRUs 102 c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. Asshown in FIG. 1A, the base station 114 b may have a direct connection tothe Internet 110. Thus, the base station 114 b may not be required toaccess the Internet 110 via the CN 106/115.

The RAN 104/113 may be in communication with the CN 106/115, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. The data may have varying qualityof service (QoS) requirements, such as differing throughputrequirements, latency requirements, error tolerance requirements,reliability requirements, data throughput requirements, mobilityrequirements, and the like. The CN 106/115 may provide call control,billing services, mobile location-based services, pre-paid calling,Internet connectivity, video distribution, etc., and/or performhigh-level security functions, such as user authentication. Although notshown in FIG. 1A, it will be appreciated that the RAN 104/113 and/or theCN 106/115 may be in direct or indirect communication with other RANsthat employ the same RAT as the RAN 104/113 or a different RAT. Forexample, in addition to being connected to the RAN 104/113, which may beutilizing a NR radio technology, the CN 106/115 may also be incommunication with another RAN (not shown) employing a GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

The CN 106/115 may also serve as a gateway for the WTRUs 102 a, 102 b,102 c, 102 d to access the PSTN 108, the Internet 110, and/or the othernetworks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) and/orthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired and/or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 112 may include another CN connected to one or more RANs, whichmay employ the same RAT as the RAN 104/113 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities (e.g., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks). For example, the WTRU 102 c shown in FIG. 1A may be configuredto communicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram illustrating an example WTRU 102. As shownin FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120,a transmit/receive element 122, a speaker/microphone 124, a keypad 126,a display/touchpad 128, non-removable memory 130, removable memory 132,a power source 134, a global positioning system (GPS) chipset 136,and/or other peripherals 138, among others. It will be appreciated thatthe WTRU 102 may include any sub-combination of the foregoing elementswhile remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In an embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and/or receive both RF and light signals. It will beappreciated that the transmit/receive element 122 may be configured totransmit and/or receive any combination of wireless signals.

Although the transmit/receive element 122 is depicted in FIG. 1B as asingle element, the WTRU 102 may include any number of transmit/receiveelements 122. More specifically, the WTRU 102 may employ MIMOtechnology. Thus, in one embodiment, the WTRU 102 may include two ormore transmit/receive elements 122 (e.g., multiple antennas) fortransmitting and receiving wireless signals over the air interface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as NR and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs and/or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, a Virtual Reality and/or Augmented Reality (VR/AR) device, anactivity tracker, and the like. The peripherals 138 may include one ormore sensors, the sensors may be one or more of a gyroscope, anaccelerometer, a hall effect sensor, a magnetometer, an orientationsensor, a proximity sensor, a temperature sensor, a time sensor; ageolocation sensor; an altimeter, a light sensor, a touch sensor, amagnetometer, a barometer, a gesture sensor, a biometric sensor, and/ora humidity sensor.

The WTRU 102 may include a full duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for both the UL (e.g., for transmission) anddownlink (e.g., for reception) may be concurrent and/or simultaneous.The full duplex radio may include an interference management unit 139 toreduce and or substantially eliminate self-interference via eitherhardware (e.g., a choke) or signal processing via a processor (e.g., aseparate processor (not shown) or via processor 118). In an embodiment,the WRTU 102 may include a half-duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for either the UL (e.g., for transmission) or thedownlink (e.g., for reception)).

FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the CN 106.

The RAN 104 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and/or receive wireless signals from, the WTRU 102a.

Each of the eNode-Bs 160 a, 160 b, 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the UL and/or DL, and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160 b, 160 c may communicate with one another over an X2 interface.

The CN 106 shown in FIG. 1C may include a mobility management entity(MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN)gateway (or PGW) 166. While each of the foregoing elements are depictedas part of the CN 106, it will be appreciated that any of these elementsmay be owned and/or operated by an entity other than the CN operator.

The MME 162 may be connected to each of the eNode-Bs 162 a, 162 b, 162 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 162 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 162 may provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM and/or WCDMA.

The SGW 164 may be connected to each of the eNode Bs 160 a, 160 b, 160 cin the RAN 104 via the S1 interface. The SGW 164 may generally route andforward user data packets to/from the WTRUs 102 a, 102 b, 102 c. The SGW164 may perform other functions, such as anchoring user planes duringinter-eNode B handovers, triggering paging when DL data is available forthe WTRUs 102 a, 102 b, 102 c, managing and storing contexts of theWTRUs 102 a, 102 b, 102 c, and the like.

The SGW 164 may be connected to the PGW 166, which may provide the WTRUs102 a, 102 b, 102 c with access to packet-switched networks, such as theInternet 110, to facilitate communications between the WTRUs 102 a, 102b, 102 c and IP-enabled devices.

The CN 106 may facilitate communications with other networks. Forexample, the CN 106 may provide the WTRUs 102 a, 102 b, 102 c withaccess to circuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. For example, the CN 106 may include,or may communicate with, an IP gateway (e.g., an IP multimedia subsystem(IMS) server) that serves as an interface between the CN 106 and thePSTN 108. In addition, the CN 106 may provide the WTRUs 102 a, 102 b,102 c with access to the other networks 112, which may include otherwired and/or wireless networks that are owned and/or operated by otherservice providers.

Although the WTRU is described in FIGS. 1A-1D as a wireless terminal, itis contemplated that in certain representative embodiments that such aterminal may use (e.g., temporarily or permanently) wired communicationinterfaces with the communication network.

In representative embodiments, the other network 112 may be a WLAN.

A WLAN in Infrastructure Basic Service Set (BSS) mode may have an AccessPoint (AP) for the BSS and one or more stations (STAs) associated withthe AP. The AP may have an access or an interface to a DistributionSystem (DS) or another type of wired/wireless network that carriestraffic in to and/or out of the BSS. Traffic to STAs that originatesfrom outside the BSS may arrive through the AP and may be delivered tothe STAs. Traffic originating from STAs to destinations outside the BSSmay be sent to the AP to be delivered to respective destinations.Traffic between STAs within the BSS may be sent through the AP, forexample, where the source STA may send traffic to the AP and the AP maydeliver the traffic to the destination STA. The traffic between STAswithin a BSS may be considered and/or referred to as peer-to-peertraffic. The peer-to-peer traffic may be sent between (e.g., directlybetween) the source and destination STAs with a direct link setup (DLS).In certain representative embodiments, the DLS may use an 802.11e DLS oran 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS)mode may not have an AP, and the STAs (e.g., all of the STAs) within orusing the IBSS may communicate directly with each other. The IBSS modeof communication may sometimes be referred to herein as an “ad-hoc” modeof communication.

When using the 802.11ac infrastructure mode of operation or a similarmode of operations, the AP may transmit a beacon on a fixed channel,such as a primary channel. The primary channel may be a fixed width(e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling.The primary channel may be the operating channel of the BSS and may beused by the STAs to establish a connection with the AP. In certainrepresentative embodiments, Carrier Sense Multiple Access with CollisionAvoidance (CSMA/CA) may be implemented, for example in 802.11 systems.For CSMA/CA, the STAs (e.g., every STA), including the AP, may sense theprimary channel. If the primary channel is sensed/detected and/ordetermined to be busy by a particular STA, the particular STA may backoff. One STA (e.g., only one station) may transmit at any given time ina given BSS.

High Throughput (HT) STAs may use a 40 MHz wide channel forcommunication, for example, via a combination of the primary 20 MHzchannel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHzwide channel.

Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz,and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may beformed by combining contiguous 20 MHz channels. A 160 MHz channel may beformed by combining 8 contiguous 20 MHz channels, or by combining twonon-contiguous 80 MHz channels, which may be referred to as an 80+80configuration. For the 80+80 configuration, the data, after channelencoding, may be passed through a segment parser that may divide thedata into two streams. Inverse Fast Fourier Transform (IFFT) processing,and time domain processing, may be done on each stream separately. Thestreams may be mapped on to the two 80 MHz channels, and the data may betransmitted by a transmitting STA. At the receiver of the receiving STA,the above described operation for the 80+80 configuration may bereversed, and the combined data may be sent to the Medium Access Control(MAC).

Sub 1 GHz modes of operation are supported by 802.11af and 802.11ah. Thechannel operating bandwidths, and carriers, are reduced in 802.11af and802.11ah relative to those used in 802.11n, and 802.11ac. 802.11afsupports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space(TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and16 MHz bandwidths using non-TVWS spectrum. According to a representativeembodiment, 802.11ah may support Meter Type Control/Machine-TypeCommunications, such as MTC devices in a macro coverage area. MTCdevices may have certain capabilities, for example, limited capabilitiesincluding support for (e.g., only support for) certain and/or limitedbandwidths. The MTC devices may include a battery with a battery lifeabove a threshold (e.g., to maintain a very long battery life).

WLAN systems, which may support multiple channels, and channelbandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include achannel which may be designated as the primary channel. The primarychannel may have a bandwidth equal to the largest common operatingbandwidth supported by all STAs in the BSS. The bandwidth of the primarychannel may be set and/or limited by a STA, from among all STAs inoperating in a BSS, which supports the smallest bandwidth operatingmode. In the example of 802.11ah, the primary channel may be 1 MHz widefor STAs (e.g., MTC type devices) that support (e.g., only support) a 1MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes.Carrier sensing and/or Network Allocation Vector (NAV) settings maydepend on the status of the primary channel. If the primary channel isbusy, for example, due to a STA (which supports only a 1 MHz operatingmode), transmitting to the AP, the entire available frequency bands maybe considered busy even though a majority of the frequency bands remainsidle and may be available.

In the United States, the available frequency bands, which may be usedby 802.11ah, are from 902 MHz to 928 MHz. In Korea, the availablefrequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the availablefrequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidthavailable for 802.11ah is 6 MHz to 26 MHz depending on the country code.

FIG. 1D is a system diagram illustrating the RAN 113 and the CN 115according to an embodiment. As noted above, the RAN 113 may employ an NRradio technology to communicate with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The RAN 113 may also be in communication with theCN 115.

The RAN 113 may include gNBs 180 a, 180 b, 180 c, though it will beappreciated that the RAN 113 may include any number of gNBs whileremaining consistent with an embodiment. The gNBs 180 a, 180 b, 180 cmay each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the gNBs 180 a, 180 b, 180 c may implement MIMO technology. For example,gNBs 180 a, 108 b may utilize beamforming to transmit signals to and/orreceive signals from the gNBs 180 a, 180 b, 180 c. Thus, the gNB 180 a,for example, may use multiple antennas to transmit wireless signals to,and/or receive wireless signals from, the WTRU 102 a. In an embodiment,the gNBs 180 a, 180 b, 180 c may implement carrier aggregationtechnology. For example, the gNB 180 a may transmit multiple componentcarriers to the WTRU 102 a (not shown). A subset of these componentcarriers may be on unlicensed spectrum while the remaining componentcarriers may be on licensed spectrum. In an embodiment, the gNBs 180 a,180 b, 180 c may implement Coordinated Multi-Point (CoMP) technology.For example, WTRU 102 a may receive coordinated transmissions from gNB180 a and gNB 180 b (and/or gNB 180 c).

The WTRUs 102 a, 102 b, 102 c may communicate with gNBs 180 a, 180 b,180 c using transmissions associated with a scalable numerology. Forexample, the OFDM symbol spacing and/or OFDM subcarrier spacing may varyfor different transmissions, different cells, and/or different portionsof the wireless transmission spectrum. The WTRUs 102 a, 102 b, 102 c maycommunicate with gNBs 180 a, 180 b, 180 c using subframe or transmissiontime intervals (TTIs) of various or scalable lengths (e.g., containingvarying number of OFDM symbols and/or lasting varying lengths ofabsolute time).

The gNBs 180 a, 180 b, 180 c may be configured to communicate with theWTRUs 102 a, 102 b, 102 c in a standalone configuration and/or anon-standalone configuration. In the standalone configuration, WTRUs 102a, 102 b, 102 c may communicate with gNBs 180 a, 180 b, 180 c withoutalso accessing other RANs (e.g., such as eNode-Bs 160 a, 160 b, 160 c).In the standalone configuration, WTRUs 102 a, 102 b, 102 c may utilizeone or more of gNBs 180 a, 180 b, 180 c as a mobility anchor point. Inthe standalone configuration, WTRUs 102 a, 102 b, 102 c may communicatewith gNBs 180 a, 180 b, 180 c using signals in an unlicensed band. In anon-standalone configuration WTRUs 102 a, 102 b, 102 c may communicatewith/connect to gNBs 180 a, 180 b, 180 c while also communicatingwith/connecting to another RAN such as eNode-Bs 160 a, 160 b, 160 c. Forexample, WTRUs 102 a, 102 b, 102 c may implement DC principles tocommunicate with one or more gNBs 180 a, 180 b, 180 c and one or moreeNode-Bs 160 a, 160 b, 160 c substantially simultaneously. In thenon-standalone configuration, eNode-Bs 160 a, 160 b, 160 c may serve asa mobility anchor for WTRUs 102 a, 102 b, 102 c and gNBs 180 a, 180 b,180 c may provide additional coverage and/or throughput for servicingWTRUs 102 a, 102 b, 102 c.

Each of the gNBs 180 a, 180 b, 180 c may be associated with a particularcell (not shown) and may be configured to handle radio resourcemanagement decisions, handover decisions, scheduling of users in the ULand/or DL, support of network slicing, dual connectivity, interworkingbetween NR and E-UTRA, routing of user plane data towards User PlaneFunction (UPF) 184 a, 184 b, routing of control plane informationtowards Access and Mobility Management Function (AMF) 182 a, 182 b andthe like. As shown in FIG. 1D, the gNBs 180 a, 180 b, 180 c maycommunicate with one another over an Xn interface.

The CN 115 shown in FIG. 1D may include at least one AMF 182 a, 182 b,at least one UPF 184 a,184 b, at least one Session Management Function(SMF) 183 a, 183 b, and possibly a Data Network (DN) 185 a, 185 b. Whileeach of the foregoing elements are depicted as part of the CN 115, itwill be appreciated that any of these elements may be owned and/oroperated by an entity other than the CN operator.

The AMF 182 a, 182 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N2 interface and may serve as acontrol node. For example, the AMF 182 a, 182 b may be responsible forauthenticating users of the WTRUs 102 a, 102 b, 102 c, support fornetwork slicing (e.g., handling of different PDU sessions with differentrequirements), selecting a particular SMF 183 a, 183 b, management ofthe registration area, termination of NAS signaling, mobilitymanagement, and the like. Network slicing may be used by the AMF 182 a,182 b in order to customize CN support for WTRUs 102 a, 102 b, 102 cbased on the types of services being utilized WTRUs 102 a, 102 b, 102 c.For example, different network slices may be established for differentuse cases such as services relying on ultra-reliable low latency (URLLC)access, services relying on enhanced massive mobile broadband (eMBB)access, services for machine type communication (MTC) access, and/or thelike. The AMF 162 may provide a control plane function for switchingbetween the RAN 113 and other RANs (not shown) that employ other radiotechnologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP accesstechnologies such as WiFi.

The SMF 183 a, 183 b may be connected to an AMF 182 a, 182 b in the CN115 via an N11 interface. The SMF 183 a, 183 b may also be connected toa UPF 184 a, 184 b in the CN 115 via an N4 interface. The SMF 183 a, 183b may select and control the UPF 184 a, 184 b and configure the routingof traffic through the UPF 184 a, 184 b. The SMF 183 a, 183 b mayperform other functions, such as managing and allocating UE IP address,managing PDU sessions, controlling policy enforcement and QoS, providingdownlink data notifications, and the like. A PDU session type may beIP-based, non-IP based, Ethernet-based, and the like.

The UPF 184 a, 184 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N3 interface, which may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between the WTRUs 102a, 102 b, 102 c and IP-enabled devices. The UPF 184, 184 b may performother functions, such as routing and forwarding packets, enforcing userplane policies, supporting multi-homed PDU sessions, handling user planeQoS, buffering downlink packets, providing mobility anchoring, and thelike.

The CN 115 may facilitate communications with other networks. Forexample, the CN 115 may include, or may communicate with, an IP gateway(e.g., an IP multimedia subsystem (IMS) server) that serves as aninterface between the CN 115 and the PSTN 108. In addition, the CN 115may provide the WTRUs 102 a, 102 b, 102 c with access to the othernetworks 112, which may include other wired and/or wireless networksthat are owned and/or operated by other service providers. In oneembodiment, the WTRUs 102 a, 102 b, 102 c may be connected to a localData Network (DN) 185 a, 185 b through the UPF 184 a, 184 b via the N3interface to the UPF 184 a, 184 b and an N6 interface between the UPF184 a, 184 b and the DN 185 a, 185 b.

In view of FIGS. 1A-1D, and the corresponding description of FIGS.1A-1D, one or more, or all, of the functions described herein withregard to one or more of: WTRU 102 a-d, Base Station 114 a-b, eNode-B160 a-c, MME 162, SGW 164, PGW 166, gNB 180 a-c, AMF 182 a-ab, UPF 184a-b, SMF 183 a-b, DN 185 a-b, and/or any other device(s) describedherein, may be performed by one or more emulation devices (not shown).The emulation devices may be one or more devices configured to emulateone or more, or all, of the functions described herein. For example, theemulation devices may be used to test other devices and/or to simulatenetwork and/or WTRU functions.

The emulation devices may be designed to implement one or more tests ofother devices in a lab environment and/or in an operator networkenvironment. For example, the one or more emulation devices may performthe one or more, or all, functions while being fully or partiallyimplemented and/or deployed as part of a wired and/or wirelesscommunication network in order to test other devices within thecommunication network. The one or more emulation devices may perform theone or more, or all, functions while being temporarilyimplemented/deployed as part of a wired and/or wireless communicationnetwork. The emulation device may be directly coupled to another devicefor purposes of testing and/or may performing testing using over-the-airwireless communications.

The one or more emulation devices may perform the one or more, includingall, functions while not being implemented/deployed as part of a wiredand/or wireless communication network. For example, the emulationdevices may be utilized in a testing scenario in a testing laboratoryand/or a non-deployed (e.g., testing) wired and/or wirelesscommunication network in order to implement testing of one or morecomponents. The one or more emulation devices may be test equipment.Direct RF coupling and/or wireless communications via RF circuitry(e.g., which may include one or more antennas) may be used by theemulation devices to transmit and/or receive data.

A communication network as described herein may be configured to includemultiple network slices, for example, as a way to virtualize thecommunication network. In a virtualized communication network, WTRUs mayreceive differentiated services provided with virtual and/or dedicatedresources. For example, a first network slice may be used to provideservices for smartphones. A second network slice may be used to providecritical services such as public safety services. A third network slicemay be used to provide IoT services to sensors, machines, and/or thelike.

FIG. 2 shows an example architecture for network slicing. The examplearchitecture may include a shared radio access network (RAN) and one ormore network slices. A network slice may include an Access and MobilityManagement Function (AMF), which may also be referred to herein as aCommon Control Plane (CP) Network Function (CCNF). A network slice mayinclude one or more Core Network (CN) Slices (CNS's). The AMF may hostfunctions such as authentication and/or mobility management functionsrelated to a network slice. The CNS may host functions (e.g., slice CPnetwork functions) such as session management functions. A WTRU may,e.g., upon registering with a network, be allocated and/or served by anAMF (e.g., with respect to at least one network slice). The WTRU may beprovided with a temporary identifier (ID) that identifies the WTRU, theAMF, and/or the association between the WTRU and the AMF.

The RAN may be configured to direct a registration message transmittedby a WTRU to an AMF. The direction may occur, for example when a WTRUfirst accesses (e.g., registers with) the network, and may be based onnetwork slice selection assistance information (NSSAI) provided by theWTRU. NSSAI may be referred to herein as and used interchangeably withassistance information and/or network slice assistance information. TheAMF may authenticate and/or register the WTRU upon receiving theregistration message directed by the RAN. A network slice selectionfunction (NSSF) may be configured to select one or more network slicesfor the WTRU. The NSSF may reside within (e.g., be a part of) the RANand/or the AMF. The NSSF may also be independent from the RAN and/or theAMF.

Network slice selection may be made based on various factors including,for example, assistance information provided by a WTRU, local policiesconfigured for a network and/or a WTRU, subscription informationassociated with a WTRU, the capabilities of a WTRU, and/or localityinformation associated with a WTRU. The selection of a network slice maycause a binding between an AMF that is serving the WTRU and at least oneCNS.

A WTRU may be configured (e.g., by a network) with assistanceinformation during various stages of the WTRU's operation. For example,a WTRU may receive assistance information from a network during aregistration procedure with a network. A WTRU may also receiveassistance information through an open mobile alliance (OMA) devicemanagement (DM) procedure and inform a network about the receivedassistance information. The WTRU may store the assistance information itreceives, and may subsequently update the stored assistance information(e.g., based on new or updated information received from the network).The WTRU may provide the original or updated assistance information to anetwork node (e.g., a RAN, an AMF, an NSSF, etc.) to request access to anetwork slice. The network node (e.g., a RAN, an AMF, an NSSF, etc.) mayuse the assistance information provided by the WTRU to select a networkslice for the WTRU.

The assistance information described herein may include one or more ofthe following. The assistance information may include an applicationidentity. The assistance information may include a tenant identity(e.g., which may identify an application service provider). Theassistance information may include a WTRU usage class. The assistanceinformation may include a device type. The assistance information mayinclude an identifier of a network type (e.g., which may identify aservice provided by the network).

The tenant identity may identify a company (e.g., an application serviceprovider) that may be using the network to provide certain types ofservices. The WTRU usage class may refer to differentiated services(e.g., services related to Massive IoT, Enhanced Mobile Broadband(eMBB), and/or Critical Communication (CriC), etc.). The device type mayindicate, for example, whether a device is a smartphone, an MTC device,etc. The device type may include a sub-type. For example, the sub-typemay indicate that an MTC device is located in a vehicle. The device typemay include one or more service sub-types. The service sub-types mayindicate, for example, that the device supports low latency and highdata rate services such as entertainment services, or that the devicesupports low data rate and low mobility (e.g., which may be the case fora sensor-type MTC device). An identifier of a network type may indicatewhether the network support for certain types of devices. For example,an “MTC network” may be used to identify a network to which an MTCdevice may access.

In certain cases, a WTRU may not have assistance information when itregisters with a network. In certain cases, a WTRU may be in possessionof assistance information but may request a PDN connection with anetwork (e.g., since the network may allow the WTRU to register with thenetwork without an IP address). The network and/or the WTRU may beconfigured with one or more rules regarding whether and/or how thenetwork and/or the WTRU may use assistance information that may becomeavailable to the WTRU after the WTRU has registered with the network.

For example, a network (e.g., an AMF, a RAN, an mobility managementfunction, etc.) may be configured to receive an NAS message (e.g., suchas an attach or registration message) from a WTRU. The network mayreceive the NAS message with or without assistance information providedby the WTRU. The network may evaluate (e.g., verify) the WTRU'ssubscription, local policy, capability (e.g., networking capability),and/or other information to determine a set of suitable (e.g.,allowable) assistance information for the WTRU (e.g., even if the WTRUhas included assistance information with the NAS message). Theassistance information determined by the network may affect whichnetwork slice(s) the WTRU may be allowed to access. Actual selection ofa network slice in accordance with the assistance information may occurat a later time, for example when the WTRU desires to use that networkslice or services provided by that network slice.

A network may determine which network slice(s) a WTRU may be allowed toaccess and/or the assistance information corresponding to those slice(s)on a per-slice basis. The network may store information regarding theallowed slice(s) and their corresponding assistance information, e.g.,as part of the WTRU's context. The network may perform the determinationand storage when services or connections associated with the slice(s)are not yet requested, for example.

When a WTRU registers with a network, the network may verify whether theWTRU is requesting a connection with and/or a service from the network.If so, the network may verify whether the connection and/or service canbe provided by a network slice that the network determines to besuitable (e.g., allowable) for the WTRU. If such a suitable networkslice exists, the network may select the network slice to provide theconnection and/or service requested by the WTRU. The network may set upthe WTRU's connection with the suitable network slice (e.g., with one ormore nodes of the suitable slice such as with an SM function of thenetwork slice).

A network may indicate to a WTRU (e.g., configure the WTRU with) a listof allowed NSSAIs. The network may provide the indication (e.g.,configuration) in an NAS message sent to the WTRU (e.g., such as anattach accept message). The network may indicate in the NAS messagewhich network slice(s) may have a connection(s) that has already beenset up for the WTRU.

A WTRU may treat the assistance information it receives from a network,e.g., as part of NAS signaling or in a response message from the network(e.g., an attach accept response message), as the latest assistanceinformation. The WTRU may update its existing assistance information, ifany, with the received information. The WTRU may perform the update evenif the WTRU has initially sent assistance information to the network.The WTRU may create and/or update local policies in accordance withreceived assistance information. For example, the WTRU may update itslocal policies to include a list of network slices that the WTRU may beallowed to access (e.g., based on allowed NSSAIs).

A WTRU may inform a higher layer about received assistance information.A WTRU may use and may include the latest assistance informationreceived from a network when the WTRU requests a connection with or aservice from a network slice. A WTRU may be configured with policiesthat may indicate whether received assistance information may or may notbe used when the WTRU requests a connection or service. A WTRU may senda request for a connection or service without including assistanceinformation. A network may select a suitable slice (e.g., a defaultslice such as a default NSI) for a WTRU, e.g., when the WTRU does notinclude assistance information in a connection and/or service request.

FIG. 3 shows another example of a network slice architecture. In thisexample architecture, an NSSF function is shown as a logical functionthat is independent of a RAN or a CCNF (e.g., an AMF). Such an NSSF maybe referred to herein as a slice selection function or SSF, for example.Using the example architecture of FIG. 3, a network slice may beconfigured to include (e.g., as a concatenation of) a RAN, a CCNF andone or more CNS's. A WTRU may be configured to receive services (e.g.,simultaneously) from one or more network slices. In such scenarios, theWTRU may be capable of communicating with the RAN, the CCNF, and themultiple network slices.

A WTRU may register with a network and may access one or more networkslices. Once associated with the one or more network slices, the WTRUmay experience changes with its configuration, operational parameters,subscription, service requirements, service/application providers,and/or the like. For example, an MTC device may be configured to be lessmobile, and as such the device's current selected network slice may betailored for stationary MTC devices. However, the service requirementsassociated with the MTC device may change, and the device may startmoving more often than before. Such service requirement changes may leadto a network slice change for the MTC device. For example, a new slicecapable of handling higher mobility and/or higher rate of communicationon the user plane may be selected for the MTC device.

One or more of the following may occur during network slice reselection.The network may determine that there is a new service requirement. Thenetwork may decide whether part or all of a network slice may bere-selected. The network may provide a WTRU with new (e.g., updated)assistance information that may reflect a new service requirement, andmay instruct the WTRU to re-register with the updated assistanceinformation, e.g., so that a new network slice may be selected to servethe WTRU. Upon receiving the new information, the WTRU may acknowledgethe receipt to the network. The network may allow a WTRU to move to anew network slice on an as-need basis. The movement (e.g., switchingbetween network slices) may be due to a subscription change implementedby an application service provider, for example.

Slice reselection may be initiated by a WTRU, for example, after theWTRU has been associated (e.g., simultaneously associated) with one ormore network slices. The WTRU may possess network slice selectionassistance information (NSSAI) that corresponds to the one or morenetwork slices associated with the WTRU. For example, the WTRU maypossess multiple sets of NSSAI, each corresponding to a network sliceassociated with the WTRU (e.g., each set of assistance information mayuniquely identify a network slice). The multiple sets of NSSAI may beprovided to the WTRU by a network, for example in a registrationprocedure with the network or upon connecting to the respective one ormore network slices.

Subsequent to being associated with the one or more network slices, theWTRU may receive, from the network, updated assistance information. Theupdated assistance information may be included in one or more messagestransmitted by the network. The updated assistance information mayindicate a change associated with a network slice that is currentlyserving the WTRU. The change may include, for example, a change in thesubscription information of the WTRU, a change in the mobility of theWTRU, a change in a service type provided by an existing network slice,a change in a service type associated with data transmitted to and/orfrom the WTRU, a change in a priority of the data transmitted to and/orfrom the WTRU, a change in an operating condition of the network, and/orthe like. The WTRU may receive the updated assistance information viaOMA DM, via a short message service (SMS), or via other higher layerprotocol. The updated assistance information may trigger the WTRU toreselect (e.g., to modify) one or more of the network slices that theWTRU is currently registered with.

A WTRU's behavior with respect to network slice selection and/orreselection may be controlled by one or more configurations of the WTRU.Such configurations may be received by the WTRU in an initialregistration procedure with the network and/or during normal operationof the WTRU after the WTRU has registered with the network. Theconfigurations may control respective priorities assigned (e.g., mapped)to one or more sets of assistance information. For example, higherpriorities may be assigned to URLLC slices, lower priorities may beassigned to eMBB slices, etc. The configurations may define localpolicies for the WTRU, which may in turn dictate how (e.g., when and/orin what type of situations) the WTRU may select, reselect, and/or accessa network slice. The WTRU may be configured to check its local policiesupon receiving a set of assistance information and determine, based onthose policies, an appropriate action to take with the assistanceinformation.

The local policies of a WTRU may control when the WTRU may use a set ofassistance information (e.g., updated assistance information) to gainaccess to a corresponding network slice. For example, the local policiesof a WTRU may dictate whether the WTRU may use a set of assistanceinformation immediately upon receiving the assistance information, orafter the WTRU has contacted the network for a certain purpose (e.g., toinform the network about the assistance information, to perform periodicregistration, etc.). In an example, the WTRU may decide to use a set ofassistance information to connect to a network slice immediately afterreceiving the assistance information if the WTRU determines, based on alocal policy associated with the assistance information, that theassistance information is configured with immediacy. In an example, theWTRU may decides to use a set of assistance information to connect to anetwork slice immediately after receiving the assistance information ifthe WTRU determines, based on a local policy associated with theassistance information, that the network slice has a higher prioritythan the priority of a network slice currently serving the WTRU. In anexample, the WTRU may delay acting upon a set of received assistanceinformation if the WTRU determines, based on a local policy associatedwith the assistance information, that no immediate action is necessaryor when the priority of the assistance information is lower than that ofa current network slice serving the WTRU.

In the case where a WTRU decides to delay acting upon a set ofassistance information, the WTRU may delay the action until the WTRU hasan opportunity to contact a network to inform the network about theassistance information. The opportunity to contact the network may arisefor a variety of reasons including, for example, transmitting mobileoriginated (MO) data (e.g., uplink data) or mobile terminated (MT) data(e.g., downlink data), network paging, periodic registration, and/or thelike.

The local policies of a WTRU may control which set of assistanceinformation may be used by the WTRU, thereby controlling which networkslice(s) the WTRU may connect to at a given time. For example, the localpolicies of the WTRU may include a list of allowed NSSAIs (e.g., NSSAIssupported by the WTRU's current serving network). The list of allowedNASSIs may be generated when the WTRU registers (e.g., via an attachmentprocedure) with the serving network and/or during normal operation ofthe WTRU after the WTRU has already registered with the network. TheWTRU may store the list of allowed NSSAIs in a memory of the WTRU (e.g.,as part of the local policies of the WTRU). Upon receiving updatedassistance information, the WTRU may check its local policies anddetermine whether the updated assistance information is among thoseallowed by the local policies (e.g., supported by the current servingnetwork). If the WTRU determines that the updated assistance is allowed,the WTRU may send a request (e.g., a session management request) to theserving network to request a connection to a network slice thatcorresponds to the updated assistance information. The connectionrequest may include a part or the entirety of the updated assistanceinformation, for example.

Although the usage of assistance information and the selection andreselection of a network slice is described in the examples above asbeing controlled by a WTRU's configurations such as local policies, theWTRU's behavior may also be controlled by information included in theassistance information itself. For instance, the assistance informationmay include an instruction for the WTRU to use a timer to control whenthe WTRU may begin using the assistance information. The assistanceinformation may specify a duration of the timer, which may cause theWTRU to wait until the specified duration has expired before using theassistance information.

Upon receiving updated assistance information, a WTRU may, e.g., basedon local policies and/or information included in the updated assistanceinformation, start a timer before taking a next action. The timer mayindicate (e.g., dictate) when the WTRU may inform a network (e.g., adifferent AMF) about the updated assistance information and/or when theWTRU may use the updated assistance information to connect to acorresponding network slice. The WTRU may inform a network (e.g., adifferent AMF) about the updated assistance information through mobileoriginated signaling. The mobile originated signaling may be unrelatedto other signaling or events that may require signaling between the WTRUand the network.

The duration of the timer described above may be pre-configured for theWTRU or may be indicated in the updated assistance information. Theduration of the timer may vary in accordance with the priority of theassistance information. For example, the duration of the timer may beset to a short value (e.g., including a zero value, which may indicateimmediacy) when the priority of the assistance information is high(e.g., higher than that of the slice(s) currently serving the WTRU).When the priority of the assistance information is low (e.g., lower thanthat of the slice(s) currently serving the WTRU), the duration of thetimer may be set to a long value.

The WTRU may enter a connected mode for various reasons before the timerdescribed above expires. For example, the WTRU may enter the connectedmode to transmit and/or receive mobile originated (MO) and/or mobileterminated (MT) data or control information. In those scenarios, theWTRU may be configured to include (e.g., piggyback) network slicerelated information in messages that are transmitted for MO and/or MTcommunication purposes.

A WTRU may be configured to, upon receiving updated assistanceinformation, replace the WTRU's current assistance information with theupdated assistance information, or update the current assistanceinformation based on the updated assistance information. For example,the WTRU may replace the current assistance information with theentirety of the received assistance information. The WTRU may also use aportion of the received assistance information to update the currentassistance information. The WTRU may be permitted to replace or updatethe current assistance information at any time after the WTRU receivesthe updated assistance information. The WTRU may inform a higher layer(e.g., higher layer applications) about potential adjustments to networkslices, services, and/or connectivity. The WTRU may inform a user of theWTRU about the potential adjustments, for example by displayinginformation regarding the potential adjustments to the user.

A WTRU may, upon determining that a new network slice is to be selectedor that one or more existing network slices are to be replaced, send acontrol plane message such as a non-access stratum (NAS) message to thenetwork that is serving the WTRU. The control plane message may indicatea desire to connect to a new network slice or to replace an existingnetwork slice. The WTRU may determine whether to use an existing AMF(e.g., an AMF currently serving the WTRU) or a new AMF for the networkslice selection and/or replacement. The WTRU may make the determinationbased on information included in updated assistance information (e.g.,as will be described in greater detail below), and/or based on localpolicies. For example, the WTRU may be pre-configured with a localpolicy indicating that the WTRU should contact a new AMF for networkslice reselection.

If the WTRU determines that an existing AMF may be used, the WTRU mayinclude a temporary ID that is associated with the existing AMF in thecontrol plane message. As described above, the temporary ID may beprovided to the WTRU in a registration procedure with the servingnetwork to identify the WTRU and/or the association between the WTRU andthe AMF. The WTRU may also include the updated assistance informationand/or an indication(s) of a priority and/or policy associated with theupdated assistance information in the control plane message.

If the WTRU determines that a new AMF is to be used, the WTRU may notinclude a temporary ID in the control plane message. Such omission maytrigger the network to select a new AMF, for example. The WTRU mayinclude the updated assistance information (e.g., a portion or theentirety of the updated assistance information) and/or an indication(s)of a priority and/or policy associated with the updated assistanceinformation in the control plane message.

A WTRU may, e.g., upon receiving updated assistance information and/orbased on local polices, send a request to deactivate a connection with anetwork slice (e.g., to detach from the network slice). For example, theWTRU may send the deactivation request when the updated assistanceinformation indicates that the WTRU's existing assistance informationassociated with the network slice has become obsolete, when the WTRUdetermines that the updated assistance information is not supported bythe network slice, etc. The WTRU may indicate, e.g., in the deactivationrequest, a reason for the deactivation. For example, the WTRU mayindicate that it is detaching itself from the network slice due to achange in assistance information or because the network slice does notsupport updated assistance information received by the WTRU.

After detaching from a network slice, the WTRU may re-attach itself tothe same or a different network slice using the updated assistanceinformation. The WTRU may provide the updated assistance information toa lower layer. The WTRU may include the updated assistance informationin a NAS message. The WTRU may delete a temporary ID (e.g., which mayrepresent the WTRU's identity) associated with the detached networkslice so that the RAN no longer routes messages (e.g., NAS messages) tothat network slice.

FIG. 4 shows an example of WTRU-initiated network slice reselection. At410, a WTRU may receive updated assistance information (Ainf) from anetwork. The updated Ainf may be included in one or more messagestransmitted by the network, for example. At 420, the WTRU may determine,based on the Ainf, whether a connection to a current network slice(e.g., a slice that is serving the WTRY) should be disconnected. TheWTRU may decide to disconnect from a current slice when the Ainfindicates that a service requirement (e.g., a latency requirement) forthe WTRU has changed, for example. If the WTRU decides to disconnectfrom the current slice at 420, the WTRU may, at 430, deactivate theconnection to the current slice.

If the WTRU decides not to disconnect from the current slice at 420, theWTRU may, at 440, check local policies to determine what type of Ainf,if any, should be included in a request to connect to a new networkslice. For example, the local policies may include a list of allowedAinfs and the WTRU may only send an Ainf if it is on the list. At 450,the WTRU may determine, e.g., based on the updated Ainf received,whether it should register with a new AMF to establish a connection tothe new network slice. If the WTRU determines at 450 that it shouldregister with a new AMF, the WTRU may send a registration request to thenew AMF in which the WTRU may include the Ainf determined at 440. TheWTRU may delete the temporary ID associated with the existing AMF if therequest is to be sent to a new AMF. If the WTRU determines at 450 thatit can use an existing AMF rather than a new AMF, the WTRU may send aslice connection request to the existing AMF in which the WTRU mayinclude the Ainf determined at 440 and a temporary ID associated withthe existing AMF.

Network slice reselection for an WTRU may be initiated by a network suchas by a RAN, an AMF and/or a CNS. The network may take one or moreactions related to the slice reselection individually or in combination.For example, the network may determine that a slice (e.g., an AMF and/ora CNS) associated with the WTRU may be changed or replaced. Thedetermination may be based on one or more of the following, for example.The determination may be based on updates of the network's policies. Thedetermination may be based on the network receiving updated subscriptioninformation associated with the WTRU (e.g., from a subscriber database).The determination may be based on the network receiving a request fromanother network component (e.g., a SM function) to reselect a slice forthe WTRU, for example due to changing load conditions. The determinationmay be based on the network receiving updated assistance informationfrom the WTRU. Such assistance information may include the WTRU's localpolicies and/or subscriber information, for example.

A network may include an NSSF configured to determine which networkslice(s) may be assigned to a WTRU. The NSSF may be an independentlogical function, e.g., as shown in FIG. 3. The network may receiveupdated assistance information from a WTRU, and may forward the updatedassistance information to the NSSF and request the NSSF to select anetwork slice for the WTRU. The NSSF may use the assistance informationin combination with other policies and/or information when selecting anetwork slice for the WTRU. Once the network slice has been selected,the NSSF may provide the network with information regarding the newlyselected network slice. Such information may include the identity of anew AMF (e.g., an AMF address), a new CNS address, a new CNS type, etc.

The network may process the information received from the NSSF. Theprocessing may include determining whether a current AMF and/or a CNSwith which the WTRU is associated may continue to serve the WTRU, orother CNS(s) and/or AMF(s) should be selected for the WTRU. Whenreferred to herein, an AMF may correspond to any function within theAMF.

If the network determines that a current AMF may continue to serve theWTRU, the network may further determine whether an existing CNS for theWTRU should be changed and/or whether other CNS(s) should be selectedfor the WTRU. The other CNS(s) may correspond to a network slice that iscapable of providing and/or managing the WTRU's connection to thenetwork, a network slice that hosts an SM function, and/or the like. Ifthe network determines that no other CNS(s) is to be selected for theWTRU, the network may stop the reselection process and may send the WTRUassistance information. The assistance information may or may not be thesame as the assistance information that the WTRU currently possesses.For example, the assistance information provided by the network may besame as an existing set of assistance information of the WTRU or mayinclude updates to the existing set of assistance information.

If the network determines that one or more other CNS's are to beselected for the WTRU, the network may determine (e.g., verify) whetherit can connect to the CNS's. The determination may be made based onlocal information possessed or derivable by the network. The localinformation may include operator defined local policies at an AMF orCCNF, for example. If the determination is that the network can connectto the other CNS's, the network may proceed to perform any of thefollowing actions. The network may deactivate connections between theWTRU and the CNS(s) that is to be replaced. The network may send adeactivation request to the WTRU indicating the connection(s) that is tobe deactivated. In the deactivation request, the network may includeupdated assistance information that may be used by the WTRU to establisha new connection(s) in the place of the connection(s) to be deactivated.The network may send a request to the WTRU to instruct the WTRU toestablish a connection(s) with the newly selected CNS(s). The networkmay send a request to the new CNS(s) (e.g., which may include a new SMfunction) to instruct the new CNS(s) to activate a connection for theWTRU.

If the network determines that it currently is not connected to the oneor more other CNS's, the network may perform one or more of thefollowing actions.

The network may start a timer to disconnect from CNS's that are to bereplaced. Upon expiration of the timer, the network may send a requestto the WTRU and/or the CNS's to be replaced (e.g., to respective SMfunctions included in those CNS's) so that connections between the WTRUand those CNS's may be deactivated.

The network may maintain a list of currently active network slices forthe WTRU. The network may be configured to update the list, e.g., afterthe WTRU is disconnected from an existing network slice and/or after anew network slice has been assigned to the WTRU.

The network may send a message (e.g., a response message or anotification message) to the WTRU indicating that a connection with adomain network name (e.g., an access point name or APN) is to bedeactivated. The network may include an indication (e.g., such as theduration of a timer) in the message to inform the WTRU when suchconnection may be deactivated. The network may include a reason forreselecting a CNS in the message.

The network may send updated assistance information to the WTRU. Theupdated assistance information may be used by the WTRU in one or moresubsequent connection requests. The network may, e.g., upon expirationof the timer described above, send a deactivation request to the WTRU todisconnect from a CNS. If no CNS to which the network is connected cancontinue to serve the WTRU, the network may send an instruction and/or anotification to the WTRU so that the WTRU may act accordingly. In anexample, the network may instruct the WTRU to detach from an existingCNS and then re-attach to the same CNS with updated assistanceinformation. In an example, the network may notify the WTRU that noservice can be provided by the network (e.g., all CNS's for the WTRU mayneed to be redirected). In an example, the network may send a request toa default AMF to serve the WTRU. The network may do so upon (e.g.,immediately upon) determining that one or more CNS's are to bereselected, or upon receiving a NAS message from the WTRU.

A WTRU may receive a message from a network indicating that a connectionis to be deactivated and/or a waiting period before the connection maybe deactivated. The WTRU may receive, in a message from the network, newand/or updated assistance information. The WTRU may inform a higherlayer about a connection that may be deactivated and a time at which thedeactivation may occur. The WTRU may start a timer, and may deactivate(e.g., locally deactivate) an affected connection upon expiration of thetimer. If no other connection exists after the deactivation, the WTRUmay send a detachment request to the network and/or may locally deletethe WTRU temporary identity associated with the network connection. TheWTRU may send a new attach message. The WTRU may include new or updatedassistance information in a radio message and/or an NAS messages.

The WTRU may update its assistance information in response to receivinginformation from the network. The WTRU may send a request for a newconnection, e.g., using the updated assistance information. The WTRU mayinclude the updated assistance information in a registration message.

A network may select a default CNS and/or a default AMF for a WTRU. Thedefault CNS and/or AMF may be preconfigured. The network may select sucha default CNS and/or AMF when the network cannot find a matching CNSand/or AMF for the WTRU based on updated assistance information providedby the WTRU and/or based on updated subscriber information associatedwith the WTRU. The network may select such a default CNS and/or AMF whenno assistance information is provided by the WTRU. In an example, thenetwork may activate a connection between the WTRU and the default CNS.In an example, the network may inform the WTRU to activate a connectionwith the default CNS and/or AMF. In an example, the network may instructthe WTRU to use updated assistance information that may correspond tothe default CNS and/or AMF. In an example, the network may update theWTRU's context, e.g., so that the default CNS and/or AMF may be markedas the WTRU's selected network slice.

A network (e.g., a RAN, an AMF or a CNS) may determine that a differentAMF may serve a WTRU. The network may make such a determination based onupdated assistance information, for example. The newly determined AMFmay serve the WTRU in addition to or in lieu of an existing AMF that iscurrently serving the WTRU. The newly determined AMF may be a defaultAMF. Upon determining that the newly determined AMF may serve the WTRU,the network may deactivate the WTRU's connection with the existing AMF.The network may send a deactivation request to a CNS (e.g., to an SMfunction of the CNS) and/or to the WTRU. The network may indicate, e.g.,in the deactivation request, that the network may no longer serve theWTRU. The network may provide the WTRU with updated assistanceinformation.

The network may, upon determining that another AMF may serve the WTRU,send a notification and/or a request to the newly determined AMFindicating that the AMF may serve the WTRU. The notification and/orrequest may include the WTRU's context and/or the WTRU's updatedassistance information. Switching a WTRU from one AMF to another AMF maybe considered a “CN slice handover.”

A WTRU may delete its temporary identity associated with a network(e.g., with a AMF) and update the WTRU's assistance information. TheWTRU may do so, for example, when the WTRU receives a detachnotification and/or request from the network. A WTRU may send aregistration message (e.g. a new attachment message) to a different AMFafter detaching from an existing AMF. The WTRU may resend theregistration message periodically. A WTRU may use new and/or updatedassistance information in a radio and/or NAS message. A WTRU may keepits temporary identity with a previous AMF. The WTRU may include thetemporary identify in NAS messages (e.g., instead of using the temporaryidentify in lower layers).

Upon determining that another AMF may be selected to serve a WTRU, anetwork may wait for the WTRU to perform a registration (e.g., aperiodic registration) and/or to send an NAS message. The network mayreceive an NAS message from the WTRU, and may forward the NAS message tothe selected AMF (e.g., using a DECOR technique). The network mayinclude the WTRU's new assistance information when forwarding the NASmessage. For example, the network may include the NAS message and/or newassistance information in a redirection request sent to a RAN. Thenetwork may include an address of the selected AMF in the redirectionrequest.

FIG. 5 shows example call flows for network slice reselection.“Assistance information” is denoted as “Ainf” in the figure.

A back-off mechanism may be implemented, for example to control whenand/or how a WTRU may connect to a network slice. The back-off mechanismmay be used to prevent a WTRU from connecting to a network slice for aperiod of time, for example. The back off mechanism may be implementedon a per slice basis.

FIG. 6 shows example message flows in an example back-off mechanismrelated to network slice selection and/or reselection. A WTRU may send arequest to connect to a dedicated slice, for example, via a sessionmanagement NAS request message. The request may include single networkslice selection assistance information (S-NSSAI). The S-NSSAI mayindicate (e.g., identify) a particular network slice with which the WTRUwants to establish a connection. An AMF serving the WTRU may be awarethat connections to the particular slice may not be established (e.g.,due to a congestion situation at the slice). The AMF may be implementedin a shared control plane part of a network slice, for example. The AMFmay become cognizant of the congestion situation based on interactionwith other network functions including but not limited to a networkslice selection function (NSSF), a network repository function (NRF), asession management function (SMF), and/or other operation andmaintenance (O&M) network functions. The AMF may use a local policy,subscription information, and/or the like to decide whether to activatea back-off mechanism (e.g., a back-off timer) in response to thecongestion situation and/or the S-NSSAI. The AMF may activate theback-off mechanism on a per slice basis. With the back-off mechanism,the AMF may refrain from forwarding the WTRU's connection request to thededicated network slice (e.g., to a session management function of thededicated network slice). The AMF may send a NAS reject message to theWTRU. The AMF may indicate a back-off mechanism (e.g., a back-off timer)to the WTRU, for example as part of the NAS reject message orindependently from the NAS reject message.

When a WTRU receives an indication of a back-off mechanism (e.g., aback-off timer) associated with a network slice and/or previouslytransmitted S-NSSAI, the WTRU may refrain from sending another sessionmanagement message or S-NSSAI to the network for the duration of theback-off timer. The WTRU may take various actions upon receiving anindication of a back-off mechanism. For example, the WTRU may halt theback-off mechanism (e.g., the WTRU may stop a back-off timer) in certainscenarios. Greater detail about the actions that may be taken by a WTRUin response to receiving an indication of a back-off mechanism areprovided below.

The back-off timer described herein may be sent by an AMF. The AMF maysend the back-off timer upon receiving a mobility management messagefrom a WTRU. The mobility management message may be a service requestmessage or a registration request message (e.g., a tracking area update(TAU) request), for example. The mobility management message may includea PDU session ID that may point to one or more established PDU sessions.The AMF may send the back-off timer in a mobility management (MM) acceptNAS message to the WTRU, in a MM reject NAS message to the WTRU, and/orthe like. The NAS message may include an indication that the back-offtimer may apply to WTRU-originated signaling for a particular dedicatednetwork slice or slice instance. Different back-off timer values may beset for different slices. The WTRU may be instructed to back-off fromconnecting to a first slice. The WTRU may be allowed to establish aconnection with a second slice during a back-off period associated withthe first slice.

A WTRU may perform one or more actions upon receiving a back-offindication (e.g., a back-off timer) for a network slice. For example,upon receiving a back-off indication, the WTRU may cease sending sessionmanagement requests for the slice that corresponds to the receivedback-off mechanism. Such a slice may be associated with certain S-NSSAItransmitted by the WTRU, for example. Upon receiving an indication for aback-off mechanism, the WTRU may refrain from re-activating (e.g., theWTRU may stop re-activating) an inactive PDU session for a congestedslice or congested NSSAI via a service request. For example, the WTRUmay not include a PDU session ID in a service request message or in amobility management message for the PDU session that is connected to anactive slice. Upon receiving a back-off indication, the WTRU mayimplicitly deactivate (e.g., without further signaling with the network)an active PDU session and/or an inactive PDU session associated with acongested slice.

A WTRU may receive an explicit indication of a back-off timer (e.g.,from the network and/or an AMF). The indication may instruct the WTRU todeactivate an inactive PDU session associated with a congested slice.The indication may instruct the WTRU to deactivate active and/orinactive PDU sessions associated with a congested slice. The WTRU mayrequest a new network slice selection policy (NSSP), e.g., from a policyfunction. The policy function may reside in a network, for example. Whenrequesting the new NSSP, the WTRU may indicate that a particular sliceis congested. The policy function may provide a new NSSAI/S-NSSAI forthe WTRU, e.g., upon receiving a request for a new NSSP from the WTRU.The WTRU may send a PDU session request (e.g., a session managementrequest) with the new S-NSSAI received from the policy function.

A WTRU may stop a back-off mechanism (e.g., a back-off timer) undercertain conditions or in response to a triggering event. For example, aWTRU may stop a back-off timer when the WTRU performs a handover from a5G system (e.g., an AMF of a 5G system) to an evolved packet core (EPC)system (e.g., an MME). A WTRU may stop the back-off timer when the WTRUreceives, from a network, an attach accept message, a TAU acceptmessage, and/or any other mobility management message that includesaccepted NSSAI and the accepted NSSAI does not include a congestedS-NSSAI value. The WTRU may stop the back-off timer when the WTRU ispaged by a network for a PDU session that belongs to a congested slice.The WTRU may stop the back-off timer when the WTRU is paged by a networkfor session management signaling associated with a PDU session thatbelongs to a congested slice. The WTRU may stop the back-off timer whenthe WTRU receives an explicit indication informing the WTRU that acongestion situation no longer exists in the corresponding networkslice. The explicit indication may be received from an AMF. The explicitindication may be received via mobility management signaling or sessionmanagement signaling, for example.

A WTRU may generate session management signaling for a congested sliceor a slice that corresponds to a congested S-NSSAI if the WTRU has datato transmit and/or receive for an emergency service or a high priorityservice. In these cases, the WTRU may send a high priority indication oran emergency request indication to a network. The indication may beincluded in a NAS message to the network, for example. Upon receivingthe indication, the network (e.g., an AMF of the network) may forwardsession management messages to a network slice even if the network sliceis congested.

As described herein, a CNS may include a session management (SM)function. The SM function may be operable to provide a connection to aWTRU when the WTRU attempts to establish a connection with a datanetwork. A WTRU may be associated with one or more CNS's. The SMfunctions of the one or more CNS's may provide multiple connections forthe WTRU. The multiple connections may be independent of each other. Theconnections may be maintained even when the WTRU is in an idle state.For example, the context of the connections may be maintained while theWTRU is in the idle state such that further signaling may not be neededto reactivate (e.g., set up) the connections. When the WTRU transitionsfrom the idle mode to a connected mode, the WTRU may readily usepreviously established connections (e.g., tunnels) to transport datapackets (e.g., IP packets).

A WTRU with multiple connections may not have data to transmit/receiveon all of the connections. Thus, it may be inefficient to generatesignaling to set up connection resources (e.g., tunnels) that the WTRUmay not use. To improve efficiency, the WTRU may be configured to set upresources only for connections that the WTRU may use, and to avoidunnecessary signaling. For example, as shown in FIG. 3, a WTRUassociated with network slices A and B may only have data to transmitover network slice A when the WTRU transitions from an idle mode to aconnected mode. In such scenarios, the WTRU and/or the network may beconfigured to not generate signaling for setting up resources fornetwork slice B.

A WTRU may be configured to reduce unnecessary signaling to and fromnetwork slices. For example, a WTRU may have multiple PDN connections.The WTRU may inform a network about which connection(s) the WTRU may usewhen the WTRU transitions from an idle mode to a connected mode. TheWTRU may inform the network about the connection(s), for example, bydoing one or more of the following. The WTRU may send the network an APNor Domain Network Name identifier associated with a connection. The WTRUmay send the network a slice identity associated with a connection. TheWTRU may send the network a service or application ID associated with aconnection. The WTRU may send the network assistance information thatmay identify a connection.

A WTRU may be configured with a policy specifying which network slice(s)the WTRU may use while transitioning from an idle mode to a connectedmode. For example, the policy may provide that the WTRU may indicate toa network that the WTRU may use all of its slices even though data maynot be available for some of the slices.

A network may set up resources for the connection(s) or network slice(s)that the WTRU indicates it may use (e.g., in response to receiving theaforementioned indication from the WTRU). The network may maintaincontext (e.g., an IP address) for the connection(s) or network slice(s)that the WTRU indicates it may not use. The network may triggersignaling in the network slice(s) that the WTRU indicates it may use.

A network may verify whether a slice request from a WTRU may be granted.A network may apply its own policy when setting up resources for a WTRU.A network may choose to set up resources for a slice that is differentfrom the slice(s) requested by a WTRU.

A WTRU (e.g., while in a connected mode) may desire to use a connectionthat is not currently used by the WTRU. The WTRU may send an NAS message(e.g., such as a mobility management or session management message) to anetwork. The NAS message may indicate that the WTRU desires to establishconnection with a certain network slice. The network may, e.g., uponreceiving the NAS message, use procedures preconfigured within a networkslice to set up resources for the WTRU. The network may send a responseto a WTRU to indicate the outcome of a slice connection request. Theresponse may include a connection ID (e.g., a temporary ID), which maybe indicative of the resources that have been set up for a particularconnection or slice.

Systems, methods, and instrumentalities have been disclosed for networkslice selection and/or reselection. A WTRU may receive updatedassistance information for network slice selection. A WTRU may beconfigured with local policies and may determine when to send updatedslice selection information to the network based on the local policies.A WTRU may receive updated assistance information from a servingnetwork. A WTRU may delete a temporary ID associated with a network andmay re-attach to the network using updated assistance information. Anetwork may determine that a slice associated with a WTRU may bereselected. A network may determine whether part or all of a slice maybe reselected, for example, depending on whether the WTRU may be servedby a partial slice. A network may select an additional or differentslice for a WTRU when the network determines that an existing slice mayno longer serve a PDN connection of the WTRU (e.g., the existing slicemay still generally support the category of devices that the WTRUbelongs to). The additional or different slice may be a default sliceconfigured to provide a default connection for the WTRU. A network mayprovide a WTRU with new assistance information. A network may indicatethat a re-attach may be implemented, for example, when a slice may notserve a WTRU.

The processes and instrumentalities described herein may apply in anycombination, may apply to other wireless technologies, and for otherservices. A WTRU may refer to an identity of the physical device, or tothe user's identity such as subscription related identities, e.g.,MSISDN, SIP URI, etc. A WTRU may refer to an application-based identitysuch as a user name that may be used for each application. The processesdescribed above may be implemented in a computer program, software,and/or firmware incorporated in a computer-readable medium for executionby a computer and/or processor. Examples of computer-readable mediainclude, but are not limited to, electronic signals (transmitted overwired and/or wireless connections) and/or computer-readable storagemedia. Examples of computer-readable storage media include, but are notlimited to, a read only memory (ROM), a random access memory (RAM), aregister, cache memory, semiconductor memory devices, magnetic mediasuch as, but not limited to, internal hard disks and removable disks,magneto-optical media, and/or optical media such as CD-ROM disks, and/ordigital versatile disks (DVDs). A processor in association with softwaremay be used to implement a radio frequency transceiver for use in aWTRU, terminal, base station, RNC, and/or any host computer.

What is claimed:
 1. A method implemented in a wireless transmit/receiveunit (WTRU), the method comprising: receiving a message from a networkthe WTRU is registered with, wherein the message comprises updatedassistance information for access the network; determining, based on theupdated assistance information, that a set of network slices associatedwith the WTRU are to be modified; updating network slice selectionassistance information (NSSAI) based on the updated assistanceinformation; determining at least a portion of the updated NSSAI to beincluded in a registration message; determining, based on the receivedmessage, that an immediate registration is needed; and transmitting theregistration message comprising at least the portion of the updatedNSSAI.
 2. The method of claim 1, wherein the updated NSSAI identifies atype of service provided by at least one network slice of the set ofnetwork slices.
 3. The method of claim 2, wherein the type of serviceincludes any of: an enhanced Mobile Broadband (eMBB) service, anultra-reliable low latency communications (UR-LLC) service, and amassive Internet of Things (mIoT) service.
 4. The method of claim 1,further comprising waiting for a duration of a back-off timer beforecontacting an access and mobility management function (AMF) to establisha connection to a network slice of the set of network slices.
 5. Themethod of claim 1, wherein the updated assistance information comprisesan indication to the WTRU to re-register with the network using theupdated assistance information.
 6. The method of claim 1, furthercomprising: transmitting an acknowledgement to the network uponreceiving the updated assistance information.
 7. The method of claim 1,wherein updating the NSSAI comprises replacing current assistanceinformation with the updated assistance information.
 8. The method ofclaim 1, wherein determining the immediate registration being neededcomprises: determining the updated assistance information to be used bythe WTRU to connect, immediately after receiving the updated assistanceinformation, to a network slice of the set of modified network slices.9. The method of claim 1, wherein determining at least the portion ofthe updated NSSAI to be included in the registration message compriseschecking one or more policies to determine a type of the updated NSSAIto be included in the registration message.
 10. The method of claim 9,wherein the one or more policies include information regarding a list ofone or more network slices that the WTRU is permitted to access.
 11. Themethod of claim 1, wherein the registration message is transmittedwithout a temporary identifier associated with an access and mobilitymanagement function (AMF) of the network.
 12. A wirelesstransmit/receive unit (WTRU) comprising: a processor configured to:receive a message from a network the WTRU is registered with, whereinthe message comprises updated assistance information for access thenetwork; determine, based on the updated assistance information, that afirst set of network slices associated with the WTRU are to be modified;update network slice selection assistance information (NSSAI) based onthe updated assistance information; determine at least a portion of theupdated NSSAI to be included in a registration message; determine, basedon the received message, that an immediate registration is needed; andtransmit the registration message comprising at least the portion of theupdated NSSAI.
 13. The WTRU of claim 11, wherein the updated NSSAIidentifies a type of service provided by at least one network slice ofthe set of network slices.
 14. The WTRU of claim 12, wherein the updatedassistance information comprises an indication to the WTRU tore-register with the network using the updated assistance information.15. The WTRU of claim 12, wherein the processor is configured totransmit an acknowledgement to the network upon receiving the updatedassistance information.
 16. The WTRU of claim 12, wherein the processoris configured to replace current assistance information with the updatedassistance information.
 17. The WTRU of claim 12, wherein the processoris configured to determine the updated assistance information to be usedby the WTRU to connect, immediately after receiving the updatedassistance information, to a network slice of the set of modifiednetwork slices.
 18. The WTRU of claim 12, wherein the processor isconfigured to check one or more policies to determine a type of theupdated NSSAI to be included in the registration message.
 19. The WTRUof claim 18, wherein the one or more policies include informationregarding a list of one or more network slices that the WTRU ispermitted to access.
 20. The WTRU of claim 12, wherein the registrationmessage is transmitted without a temporary identifier associated with anaccess and mobility management function (AMF) of the network.